1. Field of the Invention
The present invention relates to an image forming apparatus, a method for controlling the same, and a storage medium.
2. Description of the Related Art
There have been proposed technologies called “Variable Data Printing: VDP” in which data for meeting a need for each customer is printed. For VDP in digital printing, standards such as PPML, PDF/VT, or the like (VDP language) have been developed, where PPML is an abbreviation for Personalized Print Markup Language, PDF is an abbreviation for Portable Document Format, and PDF/VT is a new standard PDF format for VDP.
In the VDP language, an object in print data may be classified into a reusable object, which is used a plurality of times, and a non-reusable object. An image forming apparatus for handling VDP caches rasterized image data of a reusable object. Cache processing is processing for storing (caching) image data in a storage unit such as a cache memory or the like and reusing image data in the storage unit without generating new image data when the same image is required. The image forming apparatus executes cache processing, and thus, the number of rasterizing times to be executed by the image forming apparatus decreases, resulting in an increase in the speed of print processing. Note that cached image data is described as “cache data”.
Japanese Patent Laid-Open No. 2001-199105 discloses a variable data publishing print device that caches an image in a form used commonly across records to thereby repeatedly use the image for the records. Also, Japanese Patent Laid-Open No. 2010-044665 discloses an image processing device that performs cache processing for an image element(s) for which the effect of cache processing can be expected among image elements generated from the records.
There is a specification in which cache data after enlargement/reduction/rotation/movement (hereinafter referred to as “transformation”) of cache data is reused by an image forming apparatus. The specification is a specification based on a VDP language. Here, image data cached in a storage unit may have already been subjected to halftone processing. In this case, if the image forming apparatus reuses cache data subjected to transformation, the halftone shape of cache data may be transformed, resulting in the occurrence of image failure.